The present invention relates to a device for preventing ignition of an endotracheal tube during laser surgery. More particularly, the present invention involves detection of impingement of the laser on the endotracheal tube, and communication between the endotracheal tube and the laser in order to modulate the intensity of the laser beam impinging the endotracheal tube, and prevent ignition of the endotracheal tube.
An endotracheal tube is a tube within or passing through the trachea which opens an unobstructed airway for a patient to breathe. These tubes have numerous applications in surgical procedures, particularly in surgical procedures of the ears, nose or throat of a patient. Recently, medical advances have included the use of laser beams in surgical procedures. However, in surgical procedures of the throat, close proximity exists between the area of the patient being operated upon and the endotracheal tube. Hence, when lasers are used in such procedures, there is a real possibility of accidental impingement of the endotracheal tube with the laser beam and ignition of the endotracheal tube. Such accidental ignition can cause substantial injury to the patient. As a result, efforts have been made to minimize the potential of igniting the endotracheal tube during laser surgery.
On such effort involves providing a fire suppression and prevention assembly to the endotracheal tube, wherein the tube is surrounded by a flexible sheath that can be inflated with a non-inflammable fluid. Consequently, if the sheath is accidentally impinged with laser radiation, the airway carrying gases to the patient, e.g., oxygen, is protected and the non-inflammable fluid helps extinguish any fires before they can injure the patient. However, such a method possesses inherent limitations. In particular, the volume of the throat is extremely small. Thus, a sheath surrounding the endotracheal tube may well take up valuable space within the throat and obstruct the medical provider""s view of the area of the throat upon which is being operated.
Another method for minimizing the possibility of igniting the endotracheal tube involves a device wherein the endotracheal tube is surrounded with an airtight flexible metal tube, which is resistant to laser radiation. Such a device may also comprise an upper fluid-inflatable polymeric cuff and a lower inflatable polymeric cuff, which are inflated with a fluid (liquid) that is passed through a conduit which passes through the tube, so that the upper and lower cuffs are in fluid communication. As a result, the metal tubing protects the gas being passed to the patient from the laser, and the upper cuff protects the lower cuff from the laser beam. However, this type of a device suffers from drawbacks similar to those set forth above, i.e., it takes up a large volume in the patient""s throat obstructing the medical provider""s view, and constrains the flexibility of the endotracheal tube.
Other methods of ameliorating the possibility of ignition of the endotracheal tube include wrapping the tube in laser beam resistant material, or in a metal foil, which reflects any stray laser radiation from the endotracheal tube. The tube can also be wrapped with a material having pores of a diameter or thickness ranging from ⅕ to ⅓ of the wavelength of a laser beam used in a laser surgical procedure. However, such methods suffer from inherent limitations. For example, they limit the flexibility of the endotracheal tube. Also, these wrappings can dislodge or unwrap from the tube during surgery, leaving the endotracheal tube exposed for possible impingement by the laser beam. Another problem with such methods, particularly the metal foil wrappings, is that laser radiation reflected from the endotracheal tube can readily strike areas of the throat, injuring the patient.
Accordingly, what is needed is a new and useful device and method for preventing ignition of an endotracheal tube, wherein the device senses the impingement of laser radiation on the endotracheal tube, and then modulates the intensity of the laser radiation, preventing ignition of the endotracheal tube.
The citation of any reference herein should not be construed as an admission that such reference is available as xe2x80x9cPrior Artxe2x80x9d to the instant application.
There is provided, in accordance with the present invention, a new, useful, and unobvious device for preventing ignition of an endotracheal tube during laser surgery. Such a device grants the medical provider an unobstructed view of the patient""s throat and modulates the intensity of laser radiation entering the patient""s throat after the laser radiation has been detected impinging the endotracheal tube.
Broadly, the present invention extends to a device for preventing ignition of an endotracheal tube during laser surgery, wherein the device comprises a sensor which is associated with the endotracheal tube, which senses impingement of a laser beam onto the endotracheal tube. A device of the invention also comprises a controller which modulates the intensity of the laser beam, wherein the controller and the sensor are in communication. When the sensor senses impingement of the laser beam on the endotracheal tube, the sensor instructs the controller to modulate the intensity of the beam impinging the endotracheal tube, which prevents ignition of the endotracheal tube. In a particular embodiment, the controller impedes the laser beam.
Numerous sensors have applications in a device of the present invention. For example, a sensor of a device of the invention can comprise a wire associated with the endotracheal tube, wherein the wire is electrically connected to a power source and a microprocessor. The microprocessor is also electrically connected to the controller. The power source can produce either direct current (DC) or alternating current (AC). When an electrical parameter of the wire, e.g, resistance, voltage, current, capacitance, impedance, etc., changes due to impingement of the laser beam onto the wire, the microprocessor measures the change in the electrical parameter, and communicates that change to the controller. The controller in turn modulates the intensity of the laser beam based upon this change in the electrical parameter.
For example, in situations where the power source is supplying direct current (DC) to the sensor, the sensor can comprise a wheatstone bridge electrically connected to a wire that is associated with the endotracheal tube, wherein the wire is also electrically connected to the power source. An electrical parameter of the wire changes when the wire is impinged with the laser beam. The association of the wire can include locating the wire on the outer surface of the tube, within the lumen of the tube, within the material that forms the tube, and/or wrapping the wire around the outer surface of the tube, wherein the wire is electrically connected to the power source. The sensor can also comprise a microprocessor that is electrically connected to the wheatstone bridge and the controller. When an electrical parameter of the wire is modulated due to impingement of the laser beam on the wire, the microprocessor measures this modulation and instructs the controller modulate the intensity of the laser beam impinging the endotracheal tube. As a result, ignition of the endotracheal tube is prevented. The electrical parameter of the wire can be voltage, resistance, current, etc. One of ordinary skill in the art can readily program the microprocessor to measure a modulation in any of these parameters using routine programming techniques.
Naturally, numerous materials can be used in a wire of a device as described above. Particular examples of such materials include, but certainly are not limited to Nichrome, a composition of 80% Ni, and 20% Cr by weight, and a resistivity of 108X 108 ohm*meter.
Likewise, a large variety of lasers have applications with a device of the invention, including CO2 and excimer lasers, to name only a few.
Moreover, the association of the wire with the endotracheal tube can be that the wire is on the endotracheal tube, within the material forming the endotracheal tube, or within the lumen of the endotracheal tube. In a particular embodiment of a device of the invention, wherein the wire is on the endotracheal tube, the wire is wrapped around the endotracheal tube.
The present invention further extends to a device for preventing ignition of an endotracheal tube during surgery with a laser beam generated by a laser, the device comprising:
(a) a wire associated with the endotracheal tube, wherein the wire is electrically connected to a power source, and electrical resistance of the wire increases upon impingement of the wire by the laser beam;
(b) a wheatstone bridge electrically connected to the wire;
(c) a microprocessor electrically connected to the wheatstone bridge, wherein the microprocessor measures electrical resistance of the wire; and
(d) a controller which controls power entering the laser, and is electrically connected to the microprocessor,
such that upon laser beam""s impingement of the endotracheal tube and the wire, the microprocessor measures an increase in the electrical resistance of the wire and instructs the controller to impede power entering the laser. As a result, the laser beam is extinguished and ignition of the endotracheal tube is prevented.
Moreover, the present invention extends to a device of the present invention wherein the power source of the sensor produces alternating Current (AC) and/or radio frequency (RF). Thus, when the sensor associated with the tube is impinged by the laser beam, an electrical parameter of the sensor changes. Particular examples of AC electrical characteristics of the sensor that would change due to impingement with the laser beam include, but certainly are not limited to electrical capacitance or inductance.
Numerous sensors whose AC electrical characteristics would change due to impingement by a laser beam are well known by those of ordinary skill in the art, and are encompassed by the present invention. A particular example of such a sensor comprises:
(a) an oscillator to generate the AC frequency for sensor material excitation;
(b) an amplifier to driver to increase the power of the aforementioned AC signal;
(c) a sensing material of or associated with the endotracheal tube exhibiting a change in AC electrical characteristics of the sensing material from radiation or from heating upon impingement of the laser beam; and
(d) a conditioning circuitry to amplify and isolate the measuring signal resulting from the change in AC characteristics of sensor.
The measuring signal would then be communicated to the controller, which would modulate the intensity of the laser beam impinging the endotracheal tube, and preventing ignition of the endotracheal tube.
Numerous oscillator or AC signal generation methods are readily available to the skilled artisan, and have applications in the present invention. Examples include, but certainly are not limited to operational amplifier circuits, buffer circuits, transistor circuits, and integrated circuiting combining of combinations of the aforementioned amplifier circuits, etc.
Furthermore, numerous materials whose AC electrical characteristics change due to impingement with a laser beam have applications herein. Particular examples include dielectric materials such as polyethylene or polypropylene, to name only a few.
Likewise, numerous conditioning circuitry can be used in a device of the present invention. Examples include, but certainly are not limited to analog methods such as operational amplifier circuits, buffer circuits, transistor circuits, filter circuits, mixing circuits, and integrated circuits combining of combinations of aforementioned amplifier circuits, etc. Digital devices, such as amplifiers, filters, mixers, etc. implemented on digital microcontrollers, digital signal processors, application specific integrated circuits, gate arrays, programmable logic devices, and discrete digital logical devices, to name only a few, can also be used in conditioning circuitry in a particular embodiment of a device of the present invention.
In addition, numerous controllers and methods of controller have ready applications in a device of the present invention. Particular examples include analog methods such as comparators, differentiators, integrators, and integrated circuiting combining of combinations of aforementioned amplifier circuits, to name only a few. Numerous digital methods also have applications. Particular digital methods include, but certainly are not limited to comparators, differentiators, and/or integrators implemented on digital processing elements, e.g., microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, gate arrays, programmable logic devices, discrete digital logic devices, etc. These digital processing elements can be readily programmed using routine programming techniques well known to those of ordinary skill in the art.
Another sensor having applications in a device of the invention for preventing ignition of an endotracheal tube during laser surgery comprises a photocell associated with the endotracheal tube. The photocell is electrically connected to a power source. Upon impingement of the photocell by the laser beam, a voltage develops across the photocell. A microprocessor is electrically connected to the photocell and the controller. Using routine programming techniques well known to those of ordinary skill in the art, the microprocessor is programmed to measure the voltage across the photocell, and instruct the controller to modulate the intensity of the laser beam impinging the endotracheal tube. As a result, upon measuring a voltage across the photocell, the microprocessor instructs the controller to modulate the intensity of the laser beam, and prevents ignition of the endotracheal tube. Naturally, numerous photocells, including a photovoltaic cell and phototube, to name only a few, have applications herein. These photocells are further described infra. What""s more, a photocell associated with an endotracheal tube can be located on the endotracheal tube, within the material forming the endotracheal tube, or within the lumen of the endotracheal tube.
What""s more, the present invention further extends to a device for preventing ignition of an endotracheal tube during surger with a laser beam generated by a laser, the device comprising:
(a) a photocell associated with the endotracheal tube, wherein voltage across the photocell increases upon impingement of the photocell by the laser beam;
(b) a power source electrically connected to the photocell;
(c) a microprocessor electrically connected to the photocell, wherein the microprocessor is programmed to measure voltage across the photocell; and
(d) a controller which controls power entering the laser, and is electrically connected to the microprocessor,
such that upon laser beam""s impingement of the endotracheal tube and the photocell, the microprocessor measures voltage across the photocell and instructs the controller to modulate the intensity of the laser beam. The photocell can be associated with the endotracheal tube such that the photocell is on the endotracheal tube, within the material forming the endotracheal tube, or within the lumen of the endotracheal tube.
Naturally, numerous types of controllers, well known and readily available to the skilled artisan, have applications in a device of the invention as set forth above.
In addition, the present invention extends to a device for preventing ignition of an endotracheal tube during surgery with a laser beam generated by a laser, the device comprising:
(a) a photocell on the endotracheal tube, wherein the photocell is electrically connected to a power supply, wherein voltage across the photocell increases upon impingement of the photocell by the laser beam;
(b) a microprocessor electrically connected to the photocell wherein the microprocessor measures voltage across the photocell, and a predetermined voltage is programmed into the microprocessor; and
(c) a switch which controls power entering the laser, wherein the switch is electrically connected to the microprocessor,
such that upon laser beam""s impingement of the endotracheal tube and the photocell, the microprocessor measures voltage across the photocell and instructs the switch to impede power entering the laser when voltage measured across the photocell is greater than the predetermined voltage.
Naturally, numerous switches and methods of modulating the intensity of the laser beam in a device of the present invention have applications herein. Particular examples include, but certainly are not limited to delivery system modulators, connections to laser manufacturer equipment, and cutoffs for laser power, to name only a few.
Furthermore, a wide variety of methods for implementing a switch in a device of the present invention are available to a skilled artisan, and are encompassed by the present invention. In particular, a switch for modulating the intensity of the laser beam can comprise a mirror or surface that is reflective to the wavelength of the laser beam. An actuator, under the control of the controller of a device of the invention, would position the reflector to deflect the laser from the endotracheal tube, upon the controller""s determination that the laser beam is impinging the endotracheal tube. The reflector can be operated to deflect the laser beam onto an energy absorption material to safely absorb the laser energy. This absorption material would be associated with or connected to an energy dissipater to safely dissipate the energy of the laser beam to surrounding air. A connection to laser manufacturer equipment can comprise an output of the controller, such as a relay, transistor, digital signal, etc. When the controller determined, based upon input from the sensor, that the laser beam is impinging the endotracheal tube, output of the controller would cause the laser equipment to modulate the intensity of the laser beam. A cutoff for the laser power, which also can serve as a controller in a device of the present invention, can comprise a device controlled by the controller, wherein the cutoff modulates power to the laser equipment upon the controller""s determination of impingement of the laser beam can comprise activated by the controller. As a result, the intensity of the laser beam is modulated, and ignition of the endotracheal tube is prevented. Examples of such a device include relays, contractors, and/or transistors, to name only a few.
Optionally, the present invention can further extend to an alarm, which is visual, audible, vibrational, or a combination thereof, which alerts the medical professional that laser impingement upon the endotracheal tube has occurred. Numerous types of alarms well known to those of ordinary skill in the art can readily be incorporated into a device of the invention using routine engineering techniques.
Furthermore, the present invention extends to methods for preventing ignition of an endotracheal tube during laser surgery. Broadly, a method of the present comprises providing a sensor which can sense impingement of a laser beam; associating the sensor with the endotracheal tube, which senses impingement of a laser beam onto the endotracheal tube; and providing a controller which modulates the intensity of the laser beam, wherein the controller and the sensor are in communication. When the sensor senses impingement of the laser beam on the endotracheal tube, the sensor instructs the controller to modulate the intensity of the beam, which prevents ignition of the endotracheal tube. In a particular embodiment, the controller impedes the laser beam.
Numerous examples of sensors, controllers, power sources, etc. which have applications in a method of the invention are described above.
Accordingly, it is an object of the present invention to provide real-time information to a medical provider performing laser surgery regarding the impingement of the laser beam upon an endotracheal tube within the patient. As a result, the medical provide can extinguish the beam prior to igniting the endotracheal tube.
It is another object of the present invention to provide a feedback mechanism and communication between the laser and the endotracheal tube, such that upon impingement of the laser beam on the endotracheal tube, the intensity of the laser beam is modulated, and ignition of the endotracheal tube is prevented.